Here are two different reports with two very different conclusions about the reasons behind China's fast disappearing cultural history. See http://www.guardian.co.uk/world/2012/jan/01/china-tomb-raiders-destroy-relics and http://www.bbc.co.uk/news/world-asia-china-16367488
The first report repeats the usual "party line" of the archaeological community that the problem is due to gangs of looters working to supply collectors, particularly wealthy foreign ones. The State Department's broad import restrictions on Chinese cultural artifacts have been justified based on such reports, this despite the uncontested fact that by far the biggest collectors of ancient Chinese material are the Chinese themselves.
The second report attributes the destruction of China's cultural history to the vast construction projects going on in that quickly modernizing country. Why don't we hear more of this? Is it because such reports don't fit the narrative necessary to justify unpopular import restrictions that only impact American collectors and museums?